One of the best-known ankylosaurs, Sauropelta is known from several partial skeletons. These are important because much of the armor was in its natural position. From these, it has been possible to make the most accurate skeletal reconstructions and life restorations of any known ankylosaur.

Like all members of the family Nodosauridae, Sauropelta had a long, tapering tail without the bone-club of the members of the family Ankylosauridae. The neck of Sauropelta had long bone spikes projecting up and out; such spikes are not found in ankylosaurids. These spikes would have protected the neck from the bite of its predators, including Acrocanthosaurus, Perhaps more importantly, they would have made the animal look bigger and more dangerous. Bluffing would have allowed an animal to avoid a fight.

The armor of Sauropelta, and all ankylosaurs, formed in the skin, just like it does in modern alligators, crocodiles, and certain lizards. It got its name from this feature; its name means "lizard skin." The armor of Sauropelta consisted of rows of oval plates across the neck, back, and tail; spines and spikes along the sides; and large circular plates over the hips. Tiny, irregular pieces of armor filled the gaps between the larger plates. Even the skull had armor, with the plates tightly joined to the outer surface of the skull and jaws. This occurs in all nodosaurids and ankylosaurids, and is unique among the dinosaurs.

Sauropelta was different from many ankylosaurs because it had two types of teeth. Small pegs lined the upper front of the mouth, while leaf-shaped teeth lined both the upper and lower cheek region. The shape of the cheek teeth and their pattern of wear show that Sauropelta ate soft plants.

Some scientists think Sauropelta lived in herds, because at least five animals were found in one fossil quarry. Other animals that lived alongside Sauropelta were a large sauropod, possibly Pleurocoelus; the ornithopod Tenontosaurus; a large carnivore, which might be Acrocanthosaurus; and packs of the sickled-clawed Deinonychus.